It is often useful to know the values of the braking torques generated by electromagnetic retarders when such retarders are put into operation.
For example, such knowledge may serve to detect breakdowns or loss of efficiency in the retarders under consideration.
Such knowledge also makes it possible to adjust the real value of the torque at each instant, for example so as to maintain the torque equal to a predetermined reference value which is independent of the speed of rotation of the retarder, with this being done by correcting the electrical feed voltage applied at each instant to at least one of the rotor coils of the retarder as a function of the difference between the said reference value and the real value of the torque as measured at that instant.
Hardly any proposals have yet been made for reliable and cheap devices that enable such torques to be measured in operation.
The present invention proposes such a device suitable for measuring the braking torque generated by an electromagnetic retarder mounted on a vehicle, with measurement being performed at each instant during real operation.